//返回顶部
	var screenH=document.documentElement.clientHeight;
	    function goTopEx() { 
			var obj = document.getElementById("goTopBtn"); 
			function getScrollTop() { 
			return document.documentElement.scrollTop + document.body.scrollTop; 
			} 
			function setScrollTop(value) { 
			if (document.documentElement.scrollTop) { 
			document.documentElement.scrollTop = value; 
			} else { 
			document.body.scrollTop = value; 
			} 
			} 
			window.onscroll = function() { 
			getScrollTop() > screenH-100 ? obj.style.display = "": obj.style.display = "none"; 
			} 
			obj.onclick = function() { 
			var goTop = setInterval(scrollMove, 10); 
			function scrollMove() { 
			setScrollTop(getScrollTop() / 1.1); 
			if (getScrollTop() < 1) clearInterval(goTop); 
			} 
			} 
			} 